1. Field of the Invention
The present invention relates generally to a method for fabricating a flat display panel and more particularly to a method for fabricating a gas display panel with a monolithic structure. 2. Description of the Prior Art
In the prior art, display panels employing gas discharge are well known and a variety of such display panels have already been suggested. A typical structure of a gas display panel utilizes a pair of glass plates. A plurality of parallel conductors are formed on one surface of each of said glass plates. Preferably, the conductors are dielectrically coated to utilize the memory action by wall charges. The glass plates are placed so that the conductors on one glass plate are opposite to and orthogonal to the conductors on the other glass plate. Spacer means such as rods is placed between the glass plates at their peripheral portions thereby to define a distance between the conductors opposite to each other and accordingly a discharge gap. The intersections of the orthogonal conductors form display cells. The peripheral portions of the glass plates are sealed to form a gas discharge chamber including an ionizable gas. An example of a method of fabricating a gas display panel with such a structure is disclosed in the Japanese laid-open patent application No. 79972/73.
However, when the discharge gap is defined by placing such spacer rods at the peripheral portions of the panel, it is liable to cause variations in the discharge gap between the central portions and the peripheral portions of the panel due to the somewhat flexible nature of the glass plates. This inclination would be more marked especially in larger panels. Since a firing voltage is a function among other things of the discharge gap, such variations in the discharge gap with the positions of the cells would be a factor of preventing the reliable operation of the panel. If the number of the spacer rods were increased so as to be placed also at the central portions of the panel, the problem of the variations in the discharge gap could be relieved to some extent. However, even if the number of the spacer rods were increased, it would practically be impossible to keep the discharge gap uniform at all the cells due to the limited flatnesses of the glass plates themselves. Further, such incomplete flatnesses of the glass plates would not permit them to be placed quite close to each other, thereby resulting in preventing the increase of the cell density, accordingly the resolution, of the panel. It would be quite difficult and quite uneconomical to try to place the spacer rods precisely and to obtain completely flat glass plates.
Therefore, in order to realize a gas display panel which would provide a highly reliable operation and a higher cell density, it would be required to fabricate a gas display panel such that it would be free from restrictions by the flatnesses of the glass plates as much as possible.
The Japanese laid-open patent application No. 12/72 discloses a gas display panel with a structure wherein both sets of conductors orthogonal to each other are supported on one glass plate. One set of conductors are formed on the glass plate and dielectrically coated. The other set of conductors are formed on the dielectric coating so as to extend orthogonally to said one set of conductors. Then, a cover plate is attached to hold an ionizable gas in the areas adjacent to the sets of conductors orthogonal to each other. In ths gas display panel, said problem of the variations in the discharge gap due to the incomplete flatnesses of the glass plates may be solved since both sets of conductors orthogonal to each other are supported on one glass plate. However, in this gas display panel, gas discharge is produced along the surface of the dielectric coating near the intersections of the orthogonal conductors and cannot be produced perpendicularly to the glass plate at the intersections of the orthogonal conductors since the areas between the sets of conductors orthogonal to each other are completely filled with the dielectric coating. As the result, in this gas display panel, it has been impossible to define the cells clearly, to increase the cell density, and to obtain a high quality in the display.
The Japanese laid-open patent application No. 56059/73 also discloses a gas display panel with a structure wherein the sets of conductors orthogonal to each other having a dielectric coating therebetween are supported on one glass plate, similar to the gas display panel disclosed in said laid-open patent application No. 12/72. In this gas display panel, small cavities or blind holes are formed in the dielectric coating adjacent to the intersections of the orthogonal conductors, one for each of said intersections, thereby to provide a space for gas discharge at each of said intersections. However, in this gas display panel, it is still unable to increase the cell density since said cavities are not aligned with the intersections of the orthogonal conductors.
Further, the Japanese laid-open patent application No. 37073/73 discloses a gas display panel with a structure wherein the sets of conductors orthogonal to each other having a dielectric coating therebetween are supported on one insulating substrate. This gas display panel is provided with holes at the intersections of the orthogonal conductors, one for each of said intersections, which pass through the conductors on the dielectric coating and the dielectric coating to the surfaces of the conductors on the insulating substrate, thereby to provide spaces for gas discharge. These holes located at the intersections of the orthogonal conductors may accomplish the advantage that the spaces for gas discharge may be aligned with the intersections of the orthogonal conductors. However, these conductors are liable to be made wider in order to form such holes therethrough and this would be a problem in obtaining an increased resolution of the panel. Further, in this gas display panel, the memory action by wall charges cannot be utilized since both sets of the conductors are in direct contact with the gas in the panel.